2. Field of Use
This invention relates generally to a method for storing data in a distributed processing, interactive computer network intended to provide very large numbers of simultaneous users; e.g. millions, access to an interactive service having large numbers; e.g., thousands, of applications which include pre-created, interactive text/graphic sessions; and more particularly, to a method for storing data used in generating such applications, the method featuring steps for establishing data stores, the stores including first store portions maintained during data usage sessions and second store portions maintained during and between data usage sessions, the method also featuring steps for associating storage control parameters with the data, steps for supplying data to the stores in excess of store capacity, and steps for deleting data from the stores on a least-recently-used basis, so that data is retained at the stores dependent on the storage control parameters and data usage experience.
2. Prior Art
Interactive computer networks are not new. Traditionally they have included conventional, hierarchical architectures wherein a central, host computer responds to the information requests of multiple users. An illustration would be a time-sharing network in which multiple users, each at a remote terminal, log onto a host that provides data and software resource for sequentially receiving user data processing requests, executing them and supplying responses back to the users.
While such networks have been successful in making the processing power of large computers available to many users, problems have existed with them. For example, in such networks, the host has been required to satisfy all the user data processing requests. As a result, processing bottlenecks arise at the host that cause network slowdowns and compel expansion in computing resources; i.e., bigger and more complex computer facilities, where response times are sought to be held low in the face of increasing user populations.
Host size and complexity, however, are liabilities for interactive networks recently introduced to offer large numbers of the public access to transactional services such as home shopping, banking, and investment maintenance, as well as informational services concerning entertainment, business and personal matters.
As can be appreciated, commercial interactive networks will have to provide attractive services at low cost and with minimal response times in order to be successful. Unlike military and governmental networks where, because of the compulsory nature of the service performed, costs, content and efficiency are of secondary concern, in commercial services, since use is predominantly elective, and paid for by the consumer, costs will have to be held low, content made interesting and response times reduced in order to attract and hold both users who would subscribe to the service and merchandisers who would rely on it as a channel of distribution for their good and services. Accordingly, and as will be appreciated, the ability of the network to rapidly satisfy large numbers of user requests with minimal resources is fundamental to the ultimate success of the network.
As pointed out in our parent application, Ser. No. 388,156 filed Jul. 28, 1989, now issued as U.S. Pat. No. 5,347,632, breakthrough performance improvement, essential to the feasibility of broad-based, interactive services can be realized by storing application data local to the user sites and relying on the user site computing resources to manage the interactive session. As more fully described in our parent application, by locating application data closer to the user, for example, at the user terminal configured as a reception system and/or a concentrator facility hierarchically disposed between the reception system and the service host, line traffic and associated response time that would otherwise be required to retrieve data from a conventional, time-share host can be substantially reduced. Further, since the host and concentrator computers of the reception-system based systems we described can be configured as server facilities, they can be provided substantially less expensively than conventionally time-share hosts, thereby, reducing the capital and operating costs required for the service.
However, formulating storage facilities for use in such a network is not without significant problems. As will be appreciated, the amount of storage capacity available at conventional user sites, and for that matter, concentrator facilities, is limited. Accordingly, because of capacity limitations, it would not be physically and economically practical to attempt to store the entire service database at the reception system or concentrator sites. Further, even if storage capacity sufficient to accommodate substantial portions, if not all, of the service database could be provided, the need to maintain the application data current would foreclose storing all data locally or at the concentrator. As will be appreciated, the data for numerous applications of a successful interactive service must remain current for the service to be commercially viable. News stories, stock quotes, prices of goods, as well as items like airline and entertainment seating and scheduling are all time sensitive and must be regularly updated to avoid inconvenience and potential legal liability. Accordingly, even if all data could be provided locally, it would be unwise and objectionable to do so.